Integration with ONES.cn

Epic link: &5310

License: Premium. Only for JiHu, SaaS and Self-Managed.

• Test API with ONES team
• Collaborate with frontend
• Upstream MR code review

All in one draft MR: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/91842

• Make the GraphQL doc generated by gitlab:graphql:compile_docs consistent with Upstream
• Combine models of JH and Upstream for Import/Export test !861 (merged)
• Add Feature Flag ff_ones_issues_integration
• Add Ones model and config settings !733 (merged)
• Add only one issue tracker limitation !876 (merged)
• Add Ones query and client !883 (merged)
• Fill ONES mock method with real request !903 (merged)
• Add routes and serializers !907 (merged)
• Add Ones menu and view !928 (merged)
• Frontend part !920 (merged)
• Add Doc (jh/doc/user/project/integrations/ones.md) !961 (merged)

ScreenShots